Downdraft wet precipitator



-A. LMESTON; DOWNDRAFT WET PRECIPTATOR.

APPLICATION FILED NOV. 25,1911.

#1,329,844, Patented Feb. 3,1920.

3&2; @fm/uw @mgm UNITED STATES PATENT OFFICE.

.ARCHIBALD F. MESTON, 0F NEW YORK, N. Y., SSIGNOR TO RESEARCHCORPORATION,

OF NEW YORK, N. Y., A CORPORATION OF N EW YORK. I

To all 'whom t may concern:

Be it'known that I, ARCHIBALD F. Mns- ToN, a citizen of the UnitedStates, residing at New York, in the county of New York and State of NewYork, have invented cer- Awhich gases or gaseous mixtures are subjectedto a preliminary treatment for the purpose of promoting the separation.of the suspended particles from the gaseous bodies.

-The object of the invention is to treat gases or gaseous mixturespreliminary to electric treatment in a precipitator with a iiuid agentto thereby put the gases, gaseous mixtures or particular gaseousconstituents into a favorable condition for the electrical treatment.

It is the particular object to bring a fluid agent in a finely dividedcondition into a near-molecular contact with a gas or gaseous mixture tobei treated tov thereby promote the susceptibility of the gas orgaseo-us mixture to electrical treatment.`

To carry out these objects I'make provisions wherebyT the fluid agent iscaused to intercept a gas stream as a whirling or churning body offinely divided particles and the resulting mixture in this condition 'ofintimate near-molecular contact is immeparatus shown in Fig. 1; and

Fig. 3 a horizontal section on line 3 3, Figl. The precipitatorstructurek comprises a skeleton frame constructed in any suitable way asof upright beams 1 interconnected bv guyv wires 2. a collectingelectrode system consisting of a plurality of vertical tubes 3 supportedby transverse webs 4 on the frame DOWNDRAFT WET PRECIPITTOR.

Specification of Letters Patent.

` Patented Feb.`3,192o.

Application filed November 26, 1917. Serial No. 204,020.

as an illustration of the usual form of discharge chambers. Both thecollecting electrodes and discharge electrodes may be constructed indifferent ways. Above the collecting electrode system is provided aclosed chamber 6 extending substantially across the whole frame andcommunicating with the tubes 3. The only access to this chamber from theoutside is through an inlet 74 through which the gases are conductedinto the precipitator.

The discharge electrodes are suspended from` a common frame 8 locatedabove the chamber 6 and supported on insulators 9 resting on the frame.Centrally on the frame 8 is supported a rod 10 extending through aninsulator 11 into the chamber 6 and carrying at its lower end atransverse frame 12 to which all the discharge electrodes are connected.At their lower ends the discharge electrodes are connected to a spacingframe 13 which is held in fixed position relatively to the generalstructure and the collecting electrodes in particular by insulators 14.These insulators may be attached to the skeleton frame in any suitable;

way as by insulating blocks 15. Weights 16 are preferably attached tothe lower ends of the wires 5 to hold them taut. The portion below thecollecting electrodes is inclosed to form a chamber 17 similar tochamber 6 and has an outlet 18 through which the treated gas is passedto a smokestack not shown). At the bottom the chamber 17 is connected tothe outside through a liquid seal 19 through which the materialcollected may be drawn ofi' without allowing the gases to pass out.

In the chamber 6, which I term the mixing chamber, I have placed asystem of nozzles 2O connected to a liquid supply as for instance waterby a pipe 21 which may be controlled by a valve 22. These nozzles are soconstructed and disposed as to produce conjunctively a line lsprayuniformly distributed across the chamber 6 to intercept the entire gasstream, thoroughly mix with it and the suspended particles. 'The nozzle2O may be disposed in various ways tp insure a thorough mixing of thespray with the gases, but I have found'that the arrange- -llt ment shownin lFigs. 2 and 3 gives particularly good results, since the impact ofthe atomized particles of liquid on the gas tream andthe particlessuspended therein. due to the uniformly angular position of the nozzlesrelatively to each other, sets up a whirling or churning motion at rightangle to the tubes 3.

The tubes or pipes `3 have preferably a daring mouth at the upper aswell as the lower end. llt has been found thatlan excess of liquidsuspended in the gases at the upper end and an agglomerate ofprecipitated particles at the lower end is likely to cause undesirabledisruptive discharges. By expanding the pipes 3 this contingency ispractically obviated.

The spray is normally A.so adjusted by means of the valve control 22that after thorough mixing an excess of the iinely divided liquidparticles coalesces to cause a film or thin sheet of liquid tocontinuously run down the walls of .the collecting electrodes. The heavycharge of atoniized liquid increases considerably the specific gravityof the gaseous mixture and this factor together with the kinetic energyof the gases developed in a downward direction facilitates theprecipitation of the suspended particles. The above can be illustratedby describing the use of the apparatus for removing from 'la gaseousmixture the soot or carbon blaclr arising from a bituminous coal burningfurnace.

As it is well known, the soot particles given olf when coal is burned,leave the fuel in a finely divided state, probably approaching themolecular in size, but they tend to ag glomerate'as they arecarriedthrough the furnace dues. imperfect combustion of bituminous coalalso gives ott tarry'particles,

lso

especially at those portions ofthe fuel bed wherethe temperature iscomparatively low.

These tarryvparticles combine or agglomerate with the soot particles butthe' resulting material is in very une state of subdivision even whenleaving a smoke stach as the familiar black smoke.9 lt is an extremelydipicult matter to wet line soot particles. with water when they aremixed with water in the usual waysgespecially is this true when theparticles are coated with tarry substances..

-WVhem as before described, the gases are intermixed with the mistproduced by the atomized water, all that is needed is some action tobring the suspended particles and the atomized Water together. lf thereis a pronounced affinity of the particles for the liquid this will comeabout rapidly and with` out the introduction of special methods. ln

the case of tarry soot and water mist, however, this does not occur andspecial means are necessary to bring about the wetting of the particles.This is accomplished in the recente apparatus described by the use of anelectric field and preferably by the additional use of a coronadischarge accompanying the electric lield. lin the discharge chambersWhere this wetting occurs the particles of water and the suspended sootparticles are both removed from the gases by action of the electriciield and are thrown against the collecting electrodes, vl. c., thewalls of the tubes 3, and are intimately mixed on the surface thereof..'lhe removed material would normally adhere to the collectingelectrodes but in this'apparatus the excessive water present forms acontinuously running lmcon the surface of the collecting electrodes andwashes the deposited material down into the sump 19. This apparatus alsopermits the use of the phenomenon of water particles becoming nuclei forions and thereby becoming more actively attractive to suspendedparticles, thereby wetting them and removing them from the gases.

lncidentally liquid has the advantages of giving the gases betterelectric characteristics and adds materially to the success of theprocess of removing the suspended particles.

'llhe above described manner of treating gases has particular utilityin` connection with electrical precipitation for the collection ofcombustible materials which ordinarily would catch fire from theelectric discharge in precipitators as ordinarily operated. By theintimate mixture of such ma- .terials with a spray of a non-inflammableliquid, such as watertfor instance, the dan ger isavoided.

ln' the cla1ins,iin the absence of a better term, lt use the termnon-wettable to dene the 'characteristic' of a certain class ofsubstances which do not have an affinity for waterland-therefore are notreadily wetted when brought into contact with water vor other suitableliquid.

- ll claimtl.` The metliod Vof removing suspended particlesfroin gaseswhich consists in adding a liquid in the form ofl a inist to the gasesandsubjecting the gases and mist to the action of an electric eld.

2. The method of removing suspended particles from gases which consistsin adding to the gases liquid in finely divided form and in greaterquantity .than will be evaporated at that temperature of the gases whichwill result from the addition of said liquid and then subjecting thegases to the action of. an electric held.

' 3. rll`he method r of removing suspended particles fro-mgases whichconsists in passing the gases through a; zone of nely divided liquid,supplying the liquid at a rate which is in excess of that at which theliquid is evaporated under prevailing temperature conditions of thegases and subjecting the mixture of gases and liquid to the action of anelectric field.

4. The method of removing suspended solid particles from gases Whichconsists in spraying the gases Withliquid and passing the mixture ofgases and suspended solid and liquid particles into an electric Field.

5. The method of removing. solid parti-A cles from gases Which'consistsin introducing liquids into the gases in linely divided form,electrically .precipitating the solid and liquid particlessimultaneously to form a sludge.

6. The method of removing solid particles from gases which consists inintroducing liquids into the gases in iinely divided form, electricallyprecipitatingthe solid and liquid particles simultaneously to form asludge and recovering said sludge by gravity settling.

7., The method of removing non-Wettahle particles from gases, whichconsists in adding a liquid in the form of a mist to the gasescontaining the particles in suspension and subjecting the gases and mistto the action of an electric field. H

8. A method of removing suspended particles from smoke, which consistsin adding a liquid in the form of a mist to the smoke and subjecting thesmoke and mist to the action of an electric field.

9. The method of removing non-Wettable particles from a gas, whichconsists in adding a liquid in the form of a mist tothe gases containingthe particles in suspension in such a Way as to intimately mix the gasand the mist and then subjecting the mixture to the action of anelectric field.

10. The method of removing suspended particles from smoke, Whichconsists in adding a liquid in the form of a mist to the smoke in such aWay as to intimately mix the smoke and the mist and then subjecting themixture to the action of an electric iield.

11. In an apparatus for treating gaseous bodies, the combination With 4avertically disposed electrical discharge chamber, of a gas receivingchamber immediately above the discharge chamber, means for discharging afluid into the receiving chamber in a nely divided condition, and meansfor mixing the incoming gas and the said fluid.

12. In an apparatus for treating gaseous bodies, the combination with avertically disposed electrical discharge chamber, of a gas receivingchamber immediately above the discharge chamber, means for discharging aliquid into the receiving chamber in a iine spray, and means for mixingthe incoming gas and the said liquid spray.

13. In an apparatus for treating gaseous bodies, the combination With avertically disposed electrical discharge chamber, of a gas receivingchamber immediatelyabove the discharge chamber, means for discharging aliuid into the receiving chamber in a finely divided condition and inthe form or' a Whirl intercepting the flow of gas, said means comprisinga system of nozzles disposed in the receiving chamber in symmetricalangular relation to each other.

14. In apparatus for separating suspended particles from smoke, thecombination With a vertically disposed discharge chamber, of asmokereceiving chamber immediately above the discharge chamber, meansfor discharging a liquid into the receiving chamber in a inely dividedspray, and means for mixing the incoming smoke and the said liquid.

In testimony whereof I aiiix my signature.

ARCHIBALD F. MESTON.

